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Wikimedia Commons

Meet the American Boas

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Wikimedia Commons

If I say “boa,” you probably picture the tropical rain forests of South America, where the poster boy of the Boidae family, Boa constrictor, slithers through the brush. Your mind probably doesn’t leap to Los Angeles County or Colorado’s desert, but you’ll find boas there, too. The United States actually has two native boa species, the rubber boa (Charina bottae) and the rosy boa (Lichanura trivirgata), above. Their combined ranges cover much of the American west, from southern California up to Washington state, and from the Pacific coast east into Colorado, Wyoming, and Montana. The rubber boa even crosses the Canadian border into British Columbia, making it the most northerly member of the family. 

Rubber and rosy boas are smaller than their Central and South American cousins, usually growing no longer than 3 or 4 feet (Boa constrictor can reach up to 13 feet) and only as wide around as a golf ball. They’re also slower and more docile than the other members of the family. Rather than hissing and striking when confronted by larger predators or humans, they’ll roll themselves into tight balls, with their head protected in the center. Sometimes the rubber boa will also try to confuse its attacker by striking out with its blunt tail to further draw attention from its head and body. 

While not as impressive in size or ferocity, the American boas are formidable hunters, and kill their prey using the same method as other boas: constriction. Hunting at night when small mammals like mice, rats, shrews and voles are more active, the American boas lie in wait and then ambush prey when it gets too close. Striking quickly, they secure their meal with sharp, tiny teeth, curl around it and squeeze until it suffocates. While hunting, the rubber boa again makes use of its tail as a decoy. It slithers into rodent burrows and offers its tail to any protective parent that tries to attack while leaving the head free to consume the nesting young. 

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Name the Author Based on the Character
May 23, 2017
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